/// <summary>
/// Construct the texture downsampler
/// </summary>
/// <param name="source">Source texture to read</param>
/// <param name="target">Target texture to write to</param>
/// <param name="intermediate">Intermediate texture (if null, will be created as required)</param>
/// <param name="intermediate2">Second intermediate texture (if null, will be created as required)</param>
/// <param name="targetWidth">target width to downsample to</param>
/// <param name="targetHeight">target height to downsample to</param>
/// <param name="shaderProvider">Optional provider for downsample shaders</param>
public TextureDownsample(DrawTargetTexture2D source, DrawTargetTexture2D target, ref DrawTargetTexture2D intermediate, ref DrawTargetTexture2D intermediate2, int targetWidth, int targetHeight,
IDownsampleShaderProvider shaderProvider)
{
if (source == null ||
target == null)
throw new ArgumentNullException();
if (targetWidth <= 0 ||
targetHeight <= 0)
throw new ArgumentException("Invalid target size");
if (DrawTarget.FormatChannels(source.SurfaceFormat) != DrawTarget.FormatChannels(target.SurfaceFormat))
throw new ArgumentException("source.SurfaceFormat has a different number of channels than target.SurfaceFormat");
if (targetWidth > target.Width ||
targetHeight > target.Height)
throw new ArgumentException("Size is larger than target");
if (targetWidth > source.Width ||
targetHeight > source.Height)
throw new ArgumentException("Size is larger than source");
if (intermediate != null)
{
if (target.SurfaceFormat != intermediate.SurfaceFormat)
throw new ArgumentException("target.SurfaceFormat != intermediate.SurfaceFormat");
if (intermediate == intermediate2)
throw new ArgumentException("intermediate == intermediate2");
}
if (intermediate2 != null)
{
if (target.SurfaceFormat != intermediate2.SurfaceFormat)
throw new ArgumentException("target.SurfaceFormat != intermediate2.SurfaceFormat");
}
int w = source.Width;
int h = source.Height;
int targetMultipleWidth = targetWidth;
int targetMultipleHeight = targetHeight;
while (targetMultipleWidth * 2 <= w)
targetMultipleWidth *= 2;
while (targetMultipleHeight * 2 <= h)
targetMultipleHeight *= 2;
DrawTargetTexture2D current = null;
Rectangle sRegion = new Rectangle(0,0,0,0);
//first pass may require that the source is sized down to a multiple of the target size
if ((double)targetWidth / (double)w <= 0.5 &&
(double)targetHeight / (double)h <= 0.5 &&
(targetMultipleWidth != w || targetMultipleHeight != h))
{
DrawTargetTexture2D go = this.PickRT(ref intermediate, ref intermediate2, source, targetMultipleWidth, targetMultipleHeight,target.SurfaceFormat);
Vector2 size = new Vector2((float)targetMultipleWidth, (float)targetMultipleHeight);
TexturedElement te = new TexturedElement(source, size, false);
te.TextureCrop = new Rectangle(0,0,w,h);
go.Add(te);
passes.Add(go);
current = go;
w = targetMultipleWidth;
h = targetMultipleHeight;
}
//downsample on the larger axis, either 2x, 4x or 8x downsampling, until reached the target size
while (target.Equals(current) == false)
{
DrawTargetTexture2D localSource = current ?? source;
double difW = (double)targetWidth / (double)w;
double difH = (double)targetHeight / (double)h;
sRegion.Width = w;
sRegion.Height = h;
sRegion.Y = localSource.Height - h;
//both width/height difference are less than 50% smaller, so a linear interpolation will do fine
if (difW > 0.5 &&
difH > 0.5)
{
//write directly to the target
DrawTargetTexture2D go = target.Clone(false, false, false);
Vector2 te_size = new Vector2((float)targetWidth, (float)targetHeight);
TexturedElement te = new TexturedElement(localSource, te_size, false);
go.AddModifier(new ScissorModifier(0, go.Height - targetHeight, targetWidth, go.Height, go));
te.TextureCrop = sRegion;
go.Add(te);
passes.Add(go);
current = go;
continue;
}
bool horizontal = difW < difH;
double dif = Math.Min(difW, difH);
int size = horizontal ? w : h;
Vector2 dir = new Vector2(0,0);
if (horizontal)
dir.X = 1.0f / localSource.Width;
else
dir.Y = 1.0f / localSource.Height;
if (dif > 0.25) // cutoff for using 2 samples
{
DrawTargetTexture2D go;
int new_width = w;
int new_height = h;
if (horizontal)
new_width /= 2;
else
new_height /= 2;
if (new_width == targetWidth && new_height == targetHeight)
go = target.Clone(false, false, false);
else
go = PickRT(ref intermediate, ref intermediate2, localSource, new_width, new_height, target.SurfaceFormat);
Vector2 se_size = new Vector2((float)new_width, (float)new_height);
ShaderElement se = new ShaderElement((shaderProvider ?? this).DownsampleShader2, se_size, false);
go.AddModifier(new ScissorModifier(0, go.Height - new_height, new_width, go.Height, go));
se.TextureCrop = sRegion;
go.Add(new Drawer(dir,se,localSource));
passes.Add(go);
w = new_width;
h = new_height;
current = go;
continue;
}
if (dif > 0.125) // cutoff for using 4 samples
{
DrawTargetTexture2D go;
int new_width = w;
int new_height = h;
if (horizontal)
new_width /= 4;
else
new_height /= 4;
if (new_width == targetWidth && new_height == targetHeight)
go = target.Clone(false, false, false);
else
go = PickRT(ref intermediate, ref intermediate2, localSource, new_width, new_height, target.SurfaceFormat);
Vector2 se_size = new Vector2((float)new_width, (float)new_height);
ShaderElement se = new ShaderElement((shaderProvider ?? this).DownsampleShader4, se_size, false);
go.AddModifier(new ScissorModifier(0, go.Height - new_height, new_width, go.Height, go));
se.TextureCrop = sRegion;
go.Add(new Drawer(dir, se, localSource));
passes.Add(go);
w = new_width;
h = new_height;
current = go;
continue;
}
// cutoff for using 8 samples
{
DrawTargetTexture2D go;
int new_width = w;
int new_height = h;
if (horizontal)
new_width /= 8;
else
new_height /= 8;
if (new_width == targetWidth && new_height == targetHeight)
go = target.Clone(false, false, false);
else
go = PickRT(ref intermediate, ref intermediate2, localSource, new_width, new_height, target.SurfaceFormat);
Vector2 se_size = new Vector2((float)new_width, (float)new_height);
ShaderElement se = new ShaderElement((shaderProvider ?? this).DownsampleShader8, se_size, false);
go.AddModifier(new ScissorModifier(0, go.Height - new_height, new_width, go.Height, go));
se.TextureCrop = sRegion;
go.Add(new Drawer(dir, se, localSource));
passes.Add(go);
w = new_width;
h = new_height;
current = go;
continue;
}
}
}
internal SinglePassTextureFilter(DrawTargetTexture2D source, DrawTargetTexture2D target)
{
if (source == null || target == null)
throw new ArgumentNullException();
if (source.SurfaceFormat != target.SurfaceFormat)
throw new ArgumentException("source.SurfaceFormat != target.SurfaceFormat");
if (source == target)
throw new ArgumentException("source == target is invalid");
if (source.Width > target.Width ||
source.Height > target.Height)
throw new ArgumentException("source is larger than target");
this.source = source;
this.targetClone = target.Clone(false,false,false);
this.targetClone.ClearBuffer.Enabled = false;
this.element = new ShaderElement(null, source.Width, source.Height,new Vector2(1,1),true);
this.targetClone.Add(element);
if (target.Width != source.Width ||
target.Height != source.Height)
{
this.targetClone.AddModifier(new Xen.Graphics.Modifier.ScissorModifier(0, 0, Math.Min(1, (source.Width) / target.Width), Math.Min(1, (source.Height) / target.Height)));
this.element.TextureCrop = new Rectangle(0, 0, Math.Min(this.source.Width, this.targetClone.Width), Math.Min(this.source.Height, this.targetClone.Height));
}
}